Process for desiccating fluid substances



R. W. G. STUTZKE.

PROCESS FOR DESlCCATiNG FLUID SUBSTANCES.

APPLICATION FILED JUNE 8, 1916.

Patented Aug. 17, 1920.

jrweni 57fi' .ZL'JWQLZM 037102566, J;W@@ WAL UNITED STATES PATENT OFFICE.

RICHARD W. G. STUTZKE, OF CHICAGO, ILLINOIS, ASSIGNOR TO CROWN MALTOSE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PROCESS FOB. DESICCATING- FLUID SUBSTANCES.

To all whom it may concern:

Be it known that I, RICHARD W. G.

STUTZKE, a subject of the Emperor of Gerproved process for accomplishing such desiccation and an improved form of apparatus for vcarrying out the process. particularly, my present invention relates to the method of desiccation described in my prior Patent No. 1,215,889, February 13, 1917. v

The invention will be more fully understood from the following detailed description and from the drawings accompanying and forming part of the same.

In the drawings, Figure liis. a diagrammatic vertical sectional view, partly in ele-' vation, of a simple form of desiccating apparatus constructed in accordance with my invention; and Fig. 2 is a top plan view of the same.

It may be said, by way of introduction, that my present process of desiccation,- like that of my prior patent referred to, involves the continuous use of the same desiccating medium, this medium being circulated and re-circulated through a practically.

closed system of conduits, nothing entering the system save the fluid to be desiccated and nothing leaving it save the desiccated product and the moisture removed therefrom. The only energy used in the process (aside from radiation and leakage losses) is, therefore, that relatively small amount required for the continuous operation of the pumps, together with those heat units actuallyrequired to evaporate the moisture from the product to be desiccated, at the working pressure. The process of my present application differs from that of my prior application in that my present process is concerned particularly with the desiccation of substances which would be injured by subjection to temperatures. substantially exceeding 212 F. The apparatus employed for carrying out the new process is correspondingly modified.

Specification of Letters Patent.

More,

Referring more particularly to the drawings, the numeral 10 designates the desiccation-chamber of my apparatus, which, as shown, is arranged horizontall the fluid to be desiccated being introduce by a spraynozzle 11 at one end of the chamber. The

bent for connection to the outlet side of a cyclone dust-collector 16.

At its outlet end the desiccatin -chamber 10 is connected with the centra inlet 17 of a centrifugal circulating pump,l 8 which may be driven by-any approvedmeans, not

shown, and which has iits tangential outlet 19 discharging into the tangential inlet. 20

Patented Aug. 17,1920.

Application filed June 8, 1916. Serial No. 102,441.

desiccating medium is suppliedto the chamof the cyclone dust-collector 16. The bottom of the dust-collectoris provided with a self-packing, four-armed dumping-gate 19, the wings of which at all times close the outlet but permit the discharge of the powder collected by revolution of the gate, as is well understood.

An exhaust-pump, illustrated as of the rotary type, and designated 21, has its inlet side connected by a conduit 22 with some portion of the desiccation apparatus, preferably with the inlet-pipe 12. I

The operation of the apparatus above described is as follows. The burner 14 having been put in operation, the circulating-pump '18 and the vacuum-pump 21 are started,

whereby the air within the apparatus is caused to travel through the heating-pipes 15, inlet 12, desiccation-chamber 10, dustcollector 16, and thence by the pipe 12 back to the heater. 7 Simultaneously, by the action of. the vacuum-pump 21 a certain proportion of the air is exhausted from the closed system, with reduction of pressure therein. When the pressure has been'reduced by the predetermined amount, for instance, to seven pounds per square inch absolute, and the temperature of the circulating medium has reached a point above the boiling-point ofwater at the pressure existing within the apparatus, the fluid to be desiccated is spra ed into the chamber 10 through the nozz e 11.

The liquid-is instantaneously evaporated and converted into superheated steam, and the dried particles of solid material are carried along to the collecting chamber 16, where they are deposited. The introduction of this additional fluid into the closed system and its evaporation therein Will cause a rise in pressure within the system which must be relieved by the vacuum-pump 21. As the apparatus continues to operate, the air within the s stem will be gradually displaced by superheated vapor resulting from the evaporation of the water or other fluid injected into the system, so that under normal operating conditions the entire system will be filled with the superheated vapors of the solution to be desiccated, this superheat ed mass serving as a desiccating medium, absorbing heat from the heater 13, and utilizing this heat for the evaporation of the fluid introduced into the system. By the action of the vacuum-pump 21, the pressure Within the system is constantly maintained at the predetermined figure, which must be sufiiciently low so that the temperature required for giving a substantial degree of superheat to the circulating medium will be so low that the desiccated product will suffer no injury. By employing sufficiently low pressures, the principle of desiccation by a circulating mass of superheated vapors may be applied to the most unstable and easily. injured organic substances, it being quite possibleto dry economically according to this method at temperatures not exceeding 100 F. where superheated steam is used as the desiccating medium. Very much lower temperatures may be employed, as is quite obvious, where the fluid introduced has a lower boiling-point or vapor-tension, as, for instance, in the desiccation of alcoholic solutions. It should further be noted as characteristic of the invention that it is ossible to condense and collect the superiieated vapors vented from the desiccation system, which is of especial advantage where a menstruum such as alcohol, naphtha, or other valuable liquid carries the solids to be dried. Such condensation may even be advantageous where aqueous solutions are employed, since b the use of a properly proportioned con enser the required vacuum may be obtained without any pump or with the use of a small condenser pump only.

While I have shown and described in considerable detail one specific embodiment of my invention and the exact manner in which the process is carried out in such embodiment, it is to be understood that this showing and description is illustrative only and for the purpose of making my invention more clear, and that I do not regard the invention as limited to these details nor to any of them, except in so far as I have included such limitations within the terms of the following claims, in which it is my intention to claim all novelty inherent in my invention as broadly as is possible in view of the prior art.

What I claim as new and desire to secure by Letters Patent is 1. The process of evaporating liquids, which consists in sprayin the liquid into an atmosphere entirely of its own vapor, circulating said atmosphere and superheating it durlng its circulation, and exhausting the evaporated liquid from the circulating system at such a rate as to maintain a subatmospheric pressure therein.

2. The process of evaporating liquids, which consists in spraying the liquid into an atmosphere entirely of its own vapor, circulating said atmosphere and super-heating it durlng its circulation, and exhausting the evaporated liquid from the circulating system at sucha rate as to maintain a subatmospheric pressure therein, and collecting the desiccated solids.

RICHARD W. G. STUTZKE. 

